The present invention relates to a shaft sealing system for an oil-lubricated shaft bearing in a stationary, externally closed housing filled with liquid vapor, such that a shaft projecting into the housing is mounted in the shaft bearing, which is sealed by means of a sealing arrangement.
A shaft sealing system of this kind is disclosed, for example, in European Patent Document Nos. EP-A-0 317 867 or EP-A-0 476 476. The shaft sealing system of each of these references comprises a labyrinth sealing arrangement. Labyrinth sealing arrangements may be used to seal shafts which are driven by a high-speed drive motor. Such drive motors include, for example, electric driving motors which drive the wheels of vehicles via a gear drive, and are externally cooled by a fan unit.
In order to allow as little liquid as possible to emerge in the form of liquid vapor from the housing in which the oil-lubricated shaft bearing is held, over as long an operating period as possible, each liquid return channel in the labyrinth sealing arrangement according to European Patent Document No. EP-A-0 317 867 or European Patent Document No. EP-A 0 476 476 has a siphon-like liquid collecting section. The siphon-like liquid collecting section is continuously filled with liquid regardless of fluctuating pressure conditions on either side of the labyrinth seal, so that the liquid return channel is blocked by the liquid in vapor-tight fashion on both sides.
German Patent Document No. DE-U-18 71 828 discloses a shaft sealing system including a return flow screw and a contact seal element. The return flow screw with its housing, and the contact seal element, are arranged radially one above the other. This arrangement is made so that the seal element is associated with a stationary part and the countersealing surface consists of a rotating part that expands in the radial direction as rotation speed rises. The sealing gap between the stationary and rotating part becomes larger as rotation speed rises, and even more lubricating oil emerges. Additional emergence of lubricating oil from the bearing installation area is counteracted by a return flow screw. However, it is not possible for the lubricating oil to be returned into the bearing installation area. Emergence of oil vapor also cannot be prevented by the return flow screw. Return flow of lubricating oil that has already emerged also cannot be achieved by means of blocking air flowing toward the bearing installation area. If the blocking air pressure is too high, bearing lubrication is impaired or even entirely eliminated.
U.S. Pat. No. 2,188,856 describes a slinger disk for oil or oil vapor emerging from a bearing. The slinger disk comprises at least two disks immovably joined to one another, and is arranged in a closed space between bearing and seal. The oil and oil vapor emerging from the bearing collect in the closed space and are swirled around by the slinger disk. Return flow of oil into the bearing is also not possible with this arrangement.
In a further embodiment, the slinger disk is arranged behind the bearing sealing ring arrangement, and thus outside the bearing housing. In this case the only purpose of the slinger disk is to prevent penetration of solid or liquid foreign substances into the bearing housing.
German Patent Document No. DE-C-930 961 discloses a shaft sealing system which comprises a stationary seal carrier and a rotating spray ring between the seal carrier and shaft. The spray ring carries at least one slinger disk, by means of which the oil emerging from the bearing is slung into an oil collection trough formed by the seal carrier. The collected oil is removed via a discharge line.